The use of aromatic polyester polyols in the production of urethane modified isocyanurate foams has become widespread. The use of such polyester is described, for example, in U.S. Pat. Nos. 4,246,365 and 4,039,487. In an article entitled "The Use of a Unique Aromatic Polyester Polyol in Urethane Modified Isocyanurate Foam Systems", (SPI ANTC, pages 348-351, R. J. Wood, 1983), the use of aromatic polyester polyols combined with various polyethers and a solubilizer known as "Compatipol CP-120" is described (note Tables 1 and 2) and relatively low viscosity polyisocyanates is described. Also described in the Wood article is the use of a compatibility aid designated as "TRITON X-100", in combination with an aromatic polyester (note FIG. 1). TRITON X-100 is an ethoxylated nonyl phenol. The use of TRITON X-100 to enhance the Freon solubility of Terate polyols is also known and described in an article entitled "Development of Lower Cost Polyurethane Modified Polyisocyanurate and Polyurethane Rigid Foams" (SPI ANTC, Vol. 25, 1979, pages 6-13).
The use of aromatic polyester polyols in combination with sucrose or sucrose-amine based polyethers and low viscosity polyisocyanates is described in U.S. Pat. Nos. 4,459,334 and 4,496,625, and "New Polyols for Urethane Modified Isocyanurate Foams" (Journal of Cellular Plastics, May-June, 1984, K. B. White et al, pages 215-219). Polyester polyols are known which are based on aromatic acids, diethylene glycol and propylene glycol (see, e.g., Technical Data Bulletin-Firemaster PHT4-diol). It is also known that Freon solubility of a polyol produced from a dimethyl terephthalate residue can be enhanced by reacting the residue with a glycol-containing dipropylene glycol (see, e.g., U.S. Pat. No. 4,346,229).
Also known are systems based on (i) polyester diols which are produced by reacting a polyalkylene terephthalate with a diol (see, e.g., U.S. Pat. No. 4,417,001), and (ii) esterified DMI oxidation residue (see, e.g., U.S. Pat. Nos. 4,237,238, 4,394,286 and 3,647,759). The use of terephthalate ester polyols is also known (see, e.g., U.S. Pat. No. 4,100,354).
Although the various systems noted have met with some success, all suffer from one or more disadvantages relating to thermal and fire performance properties and physical properties.